Display device

ABSTRACT

A light-emitting element display device includes: a display area which has an organic insulating layer that is made of an organic insulating material; a peripheral circuit area which is disposed around the display area and which has the organic insulating layer; and a blocking area that is formed between the display area and the peripheral circuit area. The blocking area includes: a first blocking area configured by only one or a plurality of inorganic material layers between an insulating base substrate and an electrode layer which covers the display area and is formed continuously from the display area, and which configures one of two electrodes for allowing the light emitting area to emit the light; and a second blocking area including a plurality of layers configuring the first blocking area, and a light emitting organic layer.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese applicationJP2013-139743 filed on Jul. 3, 2013, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a light-emitting element displaydevice, and more particularly to a light-emitting element display devicethat allows light-emitting elements which are self-luminous bodiesarranged in respective pixels to emit a light for displaying.

2. Description of the Related Art

In recent years, an image display device using self-luminous bodiescalled “organic light emitting diode (OLED)” has been put into practicaluse, hereinafter the image display device is called “organic EL(electro-luminescent) display device”. As compared with a related-artliquid crystal display device, the organic EL display device is not onlyexcellent in visibility and response speed because the self-luminousbodies are used, but also can be further thinned because no auxiliaryilluminating device such as a backlight is required.

The organic EL display device thus configured is deteriorated with theabsorption of moisture. For that reason, an organic EL panel includes acountermeasure that a sealing glass substrate is stuck onto a TFT (thinfilm transistor) substrate on which a light emitting layer is formedwith a resin for sealing.

JP 2004-335267 A and JP 2008-047515 A disclose a structure in which anorganic film is divided between a display area and an area around anoutside of the display area in view of an entry route in which themoisture arrives at the display area from the area around the outside ofthe display area through the organic film.

SUMMARY OF THE INVENTION

A sealing film is formed on a surface of a TFT substrate so as to coveran overall surface of the display area and a peripheral circuit area.However, if a foreign matter adheres to any portion in a process beforethe sealing film is formed, the portion cannot be sufficiently coveredwith the sealing film, as a result of which the portion may configurethe entry route of the moisture from the external. In particular, in adeposition process before the sealing film is formed, the foreign matterthat has adhered to a vapor deposition mask may be transferred to theTFT substrate side during the deposition process. In this case, it isconceivable that sealing using the sealing film is insufficient.

The present invention has been made in view of the above-mentionedcircumstance, and therefore an object of the present invention is toprovide an organic EL display device that can suppress a display failureattributable to the moisture entry, and maintain a long-term quality.

According to the present invention, there is provided a light-emittingelement display device including: a display area in which pixels eachhaving a light emitting area that spontaneously emits a light arearranged in a matrix and which has an organic insulating layer that ismade of an organic insulating material; a peripheral circuit area whichis disposed around the display area, in which a metal wiring or acircuit using a thin film transistor is arranged and which has theorganic insulating layer; and a blocking area that is formed between thedisplay area and the peripheral circuit area, in which the blocking areaincludes: a first blocking area configured by only one or a plurality oflayers made of inorganic material between an insulating substrate madeof a base material and an electrode layer which covers the display areaand is formed continuously from the display area, and which configuresone of two electrodes for allowing the light emitting area to emit thelight; and a second blocking area including a plurality of layersconfiguring the first blocking area, and a light emitting organic layer.

In this example, the light emitting organic layer means at least one oflayers formed between the two electrodes, and specifically includes ahole injection layer, a hole transport layer, an electron injectionlayer, and an electron transport layer in addition to a light emittinglayer that emits a light.

Also, in the light-emitting element display device according to thepresent invention, the light emitting organic layer may include a lightemitting layer that covers the display area made of an organic lightemitting material.

Also, in the light-emitting element display device according to thepresent invention, the light emitting organic layer includes any one ofa hole injection layer, a hole transport layer, an electron injectionlayer, and an electron transport layer.

According to the present invention, there is provided a method ofmanufacturing alight-emitting element display device, including thesteps of: forming a circuit including a TFT (thin film transistor) in adisplay area and a peripheral circuit area around the display area on aninsulating substrate; forming an electrode electrically connected to thecircuit in each of pixels within the display area, and an organicinsulating film formed around the electrode; depositing a light emittingorganic layer with the use of an evaporation mask having a mask areathat covers the peripheral circuit area, and comes in contact with onlythe peripheral circuit area; and forming a sealing film that covers atleast the light emitting organic layer for sealing an overall surface ofthe insulating substrate.

Also, in the method of manufacturing a light-emitting element displaydevice according to the present invention, in the step of forming thelight emitting organic layer, an inner end of the evaporation mask isarranged within a blocking area that is formed between the display areaand the peripheral circuit area.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically illustrating an organic EL displaydevice according to an embodiment of the present invention;

FIG. 2 is a plan view illustrating a configuration of a TFT substrate inthe organic EL display device;

FIG. 3 is a cross-sectional view taken along a line III-III of FIG. 2;

FIG. 4 is a flowchart illustrating a process of manufacturing theorganic EL display device according to the embodiment of the presentinvention;

FIG. 5 is a flowchart illustrating the detail of a TFT substratemanufacturing process in FIG. 4;

FIG. 6 is a diagram illustrating an light emitting organic layer formingprocess and a cathode/sealing film forming process in FIG. 5 in detail;

FIG. 7 is a diagram illustrating a light emitting organic layer formingprocess and a cathode/sealing film forming process of a TFT substrateaccording to a comparative example 1; and

FIG. 8 is a diagram illustrating a light emitting organic layer formingprocess and a cathode/sealing film forming process of a TFT substrateaccording to a comparative example 2.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be described withreference to the accompanying drawings. In the drawings, the same orequivalent elements are denoted by identical symbols, and a repetitivedescription thereof will be omitted.

FIG. 1 is a diagram schematically illustrating an organic EL displaydevice 100 according to an embodiment of the present invention. Asillustrated in the figure, the organic EL display device 100 isconfigured by an organic EL panel 200 fixedly sandwiched between anupper frame 110 and a lower frame 120. The organic EL panel 200 isconfigured by a TFT substrate 300 which will be described later, and asealing substrate not shown which is adhered to the TFT substrate 300with a transparent resin.

FIG. 2 is a plan view illustrating a configuration of the TFT substrate300. As illustrated in the figure, the TFT substrate 300 includes adisplay area 320 in which pixels 310 each having an anode electrode 359(to be described later) arranged therein, and emitting a light on thebasis of a gradation value are arranged in a matrix, a peripheralcircuit area 340 that is arranged around the display area 320 in whichvarious signal generator circuits for driving pixel circuits, and acircuit that applies a potential to a cathode electrode 357 (to bedescribed later) are formed, and a blocking area 330 that is formedbetween the display area 320 and the peripheral circuit area 340. Also,a driving IC (integrated circuit) 350 that conducts a control forallowing the respective pixels 310 in the display area 320 to emit thelight in correspondence with the gradation value is arranged on the TFTsubstrate 300.

FIG. 3 is a cross-sectional view taken along a line III-III of FIG. 2.As illustrated in FIG. 3, the TFT substrate 300 includes a pixel circuit361 and a peripheral circuit 362 made of, for example, an LTPS(low-temperature polysilicon) within inorganic insulating films 352 and353, and an organic flattening film 355 which is an organic insulatingfilm for flattening an area in which the pixel circuit 361 and theperipheral circuit 362 are mainly formed, over a glass substrate 351which is an insulating substrate. The TFT substrate 300 also includes anorganic bank 356 which is an organic insulating film formed to cover anend of a conductive film such as an anode electrode 359 formed in athrough-hole of the organic flattening film 355, and a reflection film360 that is arranged on the glass substrate 351 side of the anodeelectrode 359 for reflecting a received light. The TFT substrate 300further includes a light emitting organic layer 358 formed of a lightemitting layer that emits the light, and/or hole injection/transportlayers and electron injection/transport layers, the cathode electrode357 which is an electrode facing the anode electrode 359, and a sealingfilm 354 formed to cover the overall surface of the TFT substrate 300.

In this example, the blocking area 330 is configured to block passing ofmoisture between the display area 320 and the peripheral circuit area340. The blocking area 330 includes a first blocking area 331 spreadbetween the cathode electrode 357 and the glass substrate 351, and madeof only an inorganic material, and a second blocking area 332 includingthe respective films of the first blocking area 331, and also having thelight emitting organic layer 358. Because moisture entering from theexternal is advanced through an organic film, for example, the moisturethat has entered the peripheral circuit area 340 can be prevented fromentering the display area 320 with the provision of an area made of onlyan inorganic material.

Hereinafter, a method of manufacturing the configuration according tothis embodiment will be described together with advantages of theconfiguration according to this embodiment.

FIG. 4 is a flowchart illustrating a process of manufacturing theorganic EL display device 100 according to the embodiment of the presentinvention. As illustrated in the flowchart, in the process ofmanufacturing the organic EL display device 100, the TFT substrate 300is first manufactured in a TFT substrate manufacturing process S100, anda sealing substrate is sequentially manufactured in a sealing substratemanufacturing process S200. Then, in a TFT substrate/sealing substrateadhering process S300, the TFT substrate 300 and the sealing substratethus manufactured are adhered to each other with a transparent resin,and in an upper and lower frame fitting process S400, external members(not shown) such as a COG and an FPC are implemented, and the upperframe 110 and the lower frame 120 are fitted to those components. Withthe above processes, the organic EL display device 100 is completed.

FIG. 5 is a flowchart illustrating the detail of the TFT substratemanufacturing process S100 in FIG. 4. As illustrated in this flowchart,in the TFT substrate manufacturing process S100, a transistor circuitmade of, for example, an LTPS is first formed in a TFT circuit formingprocess S110. The anode electrode 359 and the organic bank 356 are thenformed in an anode/organic bank forming process S120. Sequentially, thelight emitting organic layer 358 is formed by vapor deposition in alight emitting organic layer forming process S130. Finally, in acathode/sealing film forming process S140, after the cathode electrode357 that covers the display area 320, and extends to the peripheralcircuit area 340 has been formed, the sealing film 354 that covers theoverall surface of the substrate is formed to complete the TFT substrate300.

FIG. 6 is a diagram illustrating the detail of the light emittingorganic layer forming process S130 and the cathode/sealing film formingprocess S140. As described above, the light emitting organic layer 358is formed by so-called “vapor deposition”. The vapor deposition isconducted in such a manner that a portion of the TFT substrate 300 whereno film is formed is covered with an evaporation mask 410, and a filmforming material is attached onto a portion of the TFT substrate 300which is not covered with the evaporation mask 410. In this embodiment,the evaporation mask 410 that comes in contact with the peripheralcircuit area 340, but comes out of contact with the display area 320 isused. Referring to FIG. 6, in order to describe the advantages of thisembodiment, a case in which a foreign matter 411 is present in a portioncorresponding to the peripheral circuit area 340 that comes in contactwith the evaporation mask 410 will be described. First, in a maskloading process S131, the evaporation mask 410 is loaded on the TFTsubstrate 300. In this example, the inner end of the evaporation mask410 is arranged in the blocking area 330 so that the light emittingorganic layer 358 is formed within the blocking area 330, takingadhesion caused by go-around of the light emitting organic layer 358 inthe deposition process into account. Then, in a deposition process S132,the light emitting organic layer 358 is deposited. In this process, itis assumed that the foreign matter 411 is transferred to the peripheralcircuit area 340 from the evaporation mask 410. Finally, in thecathode/sealing film forming process S140, the cathode electrode 357 andthe sealing film 354 are formed. However, because the sealing film 354is not appropriately formed in a portion to which the foreign matter 411adheres, the portion may configure an entry route of the moisture.

However, in the TFT substrate 300 according to this embodiment, becausethe cathode electrode 357 to the glass substrate 351 in the firstblocking area 331 are made of only the inorganic material, moisture thathas entered the peripheral circuit area 340 is blocked in the firstblocking area 331 so that the moisture can be prevented from enteringthe display area 320, as indicated by an arrow in the figure. Therefore,there can be provided the organic EL display device that can suppressthe display failure and maintain the quality for a long period.

Although the above-mentioned light emitting organic layer 358 may beformed by any number of layers, the light emitting organic layer 358 isgenerally configured by a plurality of layers. In this case, thedeposition process using the above-mentioned evaporation mask 410 isrepeated a plurality of times. Also, the plurality of layers may beconfigured by light emitting layers that emit light, or may beconfigured by a hole injection layer, a hole transport layer, anelectron injection layer, or an electron transport layer. In particular,in the organic EL display device in which the overall surface of thedisplay area 320 emit light with a single color such as white, the lightemitting layer can be configured by the light emitting organic layer358. In the organic EL display device in which the light emitting layersof RGB are formed for each of the pixels, separately, a common layerformed commonly to the respective pixels among the hole injection layer,the hole transport layer, the electron injection layer, and the electrontransport layer may be formed by the light emitting organic layer 358.

FIG. 7 is a diagram illustrating a light emitting organic layer formingprocess and a cathode/sealing film forming process of a TFT substrateaccording to a comparative example 1. The light emitting organic layerforming process and the cathode/sealing film forming process of thecomparative example 1 are identical with those in FIG. 6 in that a maskloading process S231, a deposition process S232, and a cathode/sealingfilm forming process S240 are provided, but different therefrom in thatan evaporation mask 510 is used. A mask portion of the evaporation mask510 spreads from the peripheral circuit area 340 to a portion enteringthe display area 320. For that reason, the light emitting organic layer358 formed in the deposition process S232 is formed to fall within thedisplay area 320. Also, because it is conceivable that the mask portionof the evaporation mask 510 comes in contact with the display area 320together with the peripheral circuit area 340, there is a need toconsider a foreign matter 511 transferred in the display area 320 inaddition to the foreign matter 411 transferred in the peripheral circuitarea 340. Taking the foreign matter 511 into account, in thecathode/sealing film forming process S240, the foreign matter 511 isalso transferred in the display area 320 in addition to the peripheralcircuit area 340, as a result of which a portion where the sealing film354 is not appropriately formed appears. Therefore, that portion mayform an entry route of moisture. As described with reference to FIG. 6,the moisture entry route from the peripheral circuit area 340 canprevent the moisture from entering the display area 320 due to theexistence of the blocking area 330. However, the entry route of themoisture in the display area 320 leads to the deterioration of the lightemitting organic layer 358 as it is, and causes the display failure.

FIG. 8 is a diagram illustrating a light emitting organic layer formingprocess and a cathode/sealing film forming process of a TFT substrateaccording to a comparative example 2. The light emitting organic layerforming process and the cathode/sealing film forming process of thecomparative example 2 are identical with those in FIG. 6 in that a maskloading process S331, a deposition process S332, and a cathode/sealingfilm forming process S340 are provided, but different therefrom in thatan evaporation mask 610 is used. A mask portion of the evaporation mask610 used in the comparative example 2 has a width fixed in theperipheral circuit area 340. For that reason, the light emitting organiclayer 358 formed in the deposition process S332 is formed to spread tothe peripheral circuit area 340 beyond the blocking area 330. Because itis conceivable that the mask portion of the evaporation mask 610 comesin contact with only the peripheral circuit area 340 as in FIG. 6, onlythe foreign matter 411 is considered as in FIG. 6. When the foreignmatter 411 adheres to the peripheral circuit area 340, the sealing film354 is not appropriately formed in the peripheral circuit area 340 inthe cathode/sealing film forming process S340, and this portion may formthe entry route of the moisture. In this example, because the lightemitting organic layer 358 is formed beyond the blocking area 330, ifthe moisture enters from the moisture entry route of the peripheralcircuit area 340, the moisture is not blocked in the blocking area 330,and deteriorates the light emitting organic layer 358 of the displayarea 320 through the light emitting organic layer 358, thus causing thedisplay failure.

As has been described above, in the above-mentioned embodiment, theblocking area 330 of the TFT substrate 300 has the first blocking area331 and the second blocking area 332. As a result, even if the moistureentry route is generated in the peripheral circuit area 340, themoisture can be prevented from entering the display area 320. Also, inthe light emitting organic layer forming process causing the moistureentry route, the foreign matter can be prevented from being transferredfrom the evaporation mask to the display area 320. For that reason, thesealing film 354 of the display area 320 can be appropriately formed,and the moisture can be prevented from entering the display area 320.Therefore, the organic EL display device according to this embodimentcan suppress the display failure due to the moisture entry of thedisplay area from the outside periphery, and maintain the quality for along period.

The above-mentioned embodiment can be applied to a light-emittingelement display device using the organic light emitting material.

While there have been described what are at present considered to becertain embodiments of the invention, it will be understood that variousmodifications may be made thereto, and it is intended that the appendedclaim coverall such modifications as fall within the true spirit andscope of the invention.

What is claimed is:
 1. A display device comprising: a display area on asubstrate; and an exposing area outside the display area, the displayarea comprises: a first organic insulating layer on the substrate; aplurality of first electrodes on the first organic insulating layer; asecond organic insulating layer covering edges of the plurality of firstelectrodes, the second organic insulating layer exposing parts of uppersurfaces of the plurality of first electrodes; and a sealing layercovering the plurality of first electrodes, wherein the exposing areacomprises a first exposing area where a first lower layer is not coveredwith the first organic insulating layer and the second organicinsulating layer, and the sealing layer and the first lower layer are incontact with each other in the first exposing area.
 2. The displaydevice according to claim 1, wherein the exposing area further comprisesa second exposing area where a second lower layer is not covered withthe first organic insulating layer and the second organic insulatinglayer, and the second exposing area is between the display area and thefirst exposing area.
 3. The display device according to claim 1, furthercomprising a contact area outside the display area, the contact areacomprises a wiring on the first organic insulating layer, the displayarea further comprises: an organic layer including a light emittinglayer, the organic layer covering at least one of the exposed uppersurfaces of the first electrodes; and a second electrode covering theorganic layer, wherein the organic layer and the second electrode arebetween each of the plurality of first electrodes and the sealing layer,and the second electrode is electrically connected to the wiring at thecontact area.
 4. The display device according to claim 1, wherein thesealing layer covers the plurality of first electrodes and the firstexposing area continuously.
 5. The display device according to claim 3,further comprising a driving IC on the substrate, wherein the displayarea is located between the driving IC and the contact area.